1. Field of the Invention
The invention herein relates to optical coupling in optical cable assemblies, and in particular to, use of ferrules with single mode tolerances in certain optical cable assemblies.
2. Background of the Related Art
Light propagates in “modes” or “waves.” In an open space, the waves can propagate infinitely. However, when directing and guiding modes of light using optical fiber, propagation becomes finite. Refraction and reflection that occurs in the optical fiber results in limitation of the propagation. In a data center, transmission of optical signals relies on optical cables. Use of certain components is more problematic than others.
Consider for example that recent introduction of high bandwidth cable (e.g., “OM3” fiber cabling) into data centers. Many data centers have older, “legacy” product, which (e.g., “OM2” grade fiber cabling). This OM2 fiber has an effective modal bandwidth of about 500 Mhz/km. As improvements to components within such data centers progress, there are increased instances of high bandwidth fiber (OM3 versions) being coupled to older, limited bandwidth products (OM2 versions). This results in differential mode delay (DMD) resulting in loss of bandwidth. That is, less light will propagate down the fiber because the coupling hardware does not always align the fibers on each connections center axis.
Fiber connectors provide for a number of transmission paths. For example, fiber connectors are used to join patch panels and other connectors for continued transmission paths. These fiber-to-fiber connections rely on physical contact of one fiber to another. Often these fiber-to-fiber connections do not align well, and loss occurs. One will recognize that the fiber-to-fiber connection is a source of transmission error. That is, poor alignment results in differential mode delay (DMD) which equates to signal loss.
What is needed are techniques for connecting low bandwidth optical cable (such as OM2 cabling) with higher bandwidth cabling (such as OM3 cabling), where the connecting ensures occurrence of minimal signal loss.